For several years I used to suggest a series of "Puzzles and Paradoxes" for
discussion and, at the request of some list members, I have once again agreed
to create a few more for some further hedonistic speculation.

PUZZLE & PARADOX 125

INTRODUCTORY NOTE

For newcomers to this forum, these P&Ps are Propositions, not facts or
dogmatic proclamations. They are intended to stimulate interaction among
users working in different fields, to re-examine traditional concepts, foster
distance education, question our beliefs and suggest new lines of research or
approaches to training. We look forward to responses from anyone who has
views or relevant information on the topics.

TRANSVERSUS ABDOMINIS ACTION

Here is a quick puzzle and paradox - is the role of transversus abdominis
(TVA) as supremely important as some individuals have been suggesting? After
all, the body is extremely efficient at recruiting different systems and
processes if one of the important systems involved in a given action is
injured, ill-adapted, fatigued or otherwise compromised in its ability to
offer its optimal contribution. Not only does this happen in the muscular
system, but MRIs show that this plasticity of function even happens in the
brain.

Those who work clinically often will notice how many patients with physical
differences or dysfunctions "compensate" by using different muscles or
patterns to carry out a given task without any apparent ill-effects. One
example close to home -- my paraplegic wife who is paralysed from thoracic
level T3 is able to carry out tasks that nobody should be able to do with
that level of injury, but she often does and does so without injury.

So much has been written recently about how essential transversus abdominis
is to trunk stabilisation and mobility, but has anyone ever undertaken
studies to show that people who may not be able to activate it very
effectively may compensate very effectively by using other patterns of muscle
activation and use? Is there really any convincing proof that "less than
optimal" TVA activation definitely results in significantly less efficient
and more dangerous trunk action in all daily activities?

Studies of actions other than trunk stability have shown that the same
muscles do not necessarily become involved or become involved to the same
extent or in the same pattern in different people or in the same person at
different times (e.g., there was an article in the Scientific American within
the last 2 years which used fMRI - functional MRI to demonstrate this). If
this happens with other movements, why should actions involving TVA be any
different? Is there any genuine proof, other than the current conjecture,
that TVA contributions to trunk action is not as predictable and
deterministic as is being claimed by some therapists? Does it really matter
all that much if it sometimes does not contribute as it "should" during human
movement and its decrease in function is compensated for by other muscle
actions? Are there any references which help to resolve this paradox?